As the cost and reliability of laser light sources have decreased and increased, respectively, their applications have become increasingly varied and common. One application growing increasingly popular is in the field of entertainment. Laser light sources are being used to create laser light shows, both indoors and outdoors. Indeed, modern concert tours can often be considered disappointing unless a laser light show in included.
Devices for generating laser light shows have suffered and continue to suffer from a number of drawbacks. One drawback is that the devices tend to be rather large and bulky, and therefore difficult to transport. The laser light sources themselves tend to be rather large and bulky, and a series of beam reflectors, e.g. mirrors, and converging means, e.g. lenses, are required to draw the multiple colored laser beams (e.g. red, yellow, green) into close mutual proximity to facilitate their manipulation.
Devices for generating laser light shows typically fail to take advantage of the holography generating capabilities of laser light. Rather, the devices typically will simply use the laser light sources to project brilliantly colored light patterns upon some surface.
Accordingly, a need exists for a laser light show device having an improved design to reduce its size and complexity, and means for advantageously using the laser light to create and enhance holographic imagery.
One area of increasing interest is the area of three-dimensional volumetric displays, particularly computer generated displays. The have been many problems associated with laser illuminated volumetric imaging. These problems include high "flicker" due to slow scanning speed and modulation. The advent of audio-optic (acousto-optic) modulators has dramatically improved modulation speeds, but most techniques remain clumsy and slow.
Most laser displays are merely two-dimensional projections on a two-dimensional surface. Some techniques, such as that described in U.S. Pat. No. 5,148,310, provide a depth component by rapidly spinning or oscillating the two dimensional surface. These techniques, however suffer from point-addressability and viewability problems.
It has long been known in the art that an auto-stereoscopic, three-dimensional volume display can be created by imposing a two-dimensional image on an imaging surface or display screen and the rapidly moving the imaging surface along a third axis. In the method of imaging known as angular multi-planing, the display screen is rotated about an axis so oriented as to cause the image on the screen to sweep through the desired volume of space. One such system is described in Ketchpel, U.S. Pat. No, 3,140,415 which utilizes a phosphorescent rotating screen being illuminated by fixed electron gun means. Serious drawbacks to such a system, related to the lag time of the phosphors have been discussed in detail in Muckerheide, U.S. Pat. No. 4,799,103. Additional drawbacks to such a system arise from the requirement of enclosing the screen and electron gun means in a vacuum. Muckerheide also discusses the evolution of the art towards incorporating lasers as image generation sources. Currently, such use of lasers is widely practiced and is generally preferred.
In general, all of these attempts at generating three-dimensional images utilize two-dimensional image projection techniques with mechanical scanning to produce the illusion of a third dimension. Because of limited scanning speed, image complexity must be limited to avoid excessive flicker. With these techniques, the use of phosphorescent screens to improve persistence of the image merely causes the image to smear in space.